1. Field
The present invention is related to mobile phones and in particular context “keep alive” at a radio access network (RAN) serving mobile phones comprising Wideband Code Division Multiple Access (WCDMA).
2. Background
Wireless communication networks are widely deployed to provide various services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.
WCDMA (Wideband Code Division Multiple Access) has become a third generation standard for mobile communications. The WCDMA replaces the GSM (Global System for Mobile Communications) a second generation standard, which is oriented to voice communications with limited data capability. The demand by users for not only voice communications but also Web browsing, downloading E-mail, and sending pictures has placed a demand for higher data rate capability. The WCDMA standard provides a spectrum with a 5 MHz carrier, which provides approximately a fifty times higher data rate than the second generation GSM technology. Along with the higher data rate capability come the need to use more power and in turn the need to have power savings to moderate the demand on the battery life of a mobile or cellular phone.
In a wireless network, the presence of the mobile station is maintained by the network in order to appropriately schedule resources and to successfully route and maintain communication sessions. Data received is accompanied by identification for the mobile station (or user equipment) that can assist in maintaining tracking of such presence. Conversely, mobile stations can frequently leave the coverage area of a radio access network (RAN), be turned off for an extended period, or suffer from a fading channel that prevent continued sessions via a serving RAN. Thus, it is advantageous that the RAN be allowed to release resources and to discontinue maintaining presence tracking for such a departing mobile station.
In many instances, a mobile station enters a state when no data communication sessions are active, but state synchronization with the serving RAN is desired. Thereby, future sessions can be readily initiated or the mobile station can more quickly be contacted by another station via the serving RAN. Often such mobile stations enter a power saving state where minimal transmissions should be made (data idle state). However, conventionally a layer 3 message has to be made from the mobile station to the serving RAN in order to “keep alive” the context for the mobile station at the RAN. Typically, layer 3 messages also prompt an acknowledgement from the RAN. Thus, when the mobile station has no data to communicate, such keep alive signaling consumes over the air resources, both the uplink and the downlink.